JPS6210231Y2 - - Google Patents

Description

[Detailed explanation of the idea] This invention relates to a device for improving the propulsion performance of ships.

In the case of conventional ships equipped with screw-up propellers, a rotational flow occurs in the wake of the propeller due to the rotation of the propeller, and this rotational energy is lost without being converted into thrust, which is one of the causes of a decrease in propulsion efficiency. ing. In order to reduce the rotational flow behind the propeller and improve propulsion efficiency, it has been considered to generate a flow in the opposite direction to the rotational direction of the propeller in front of the propeller. Reaction fins fixed on both sides and an asymmetrical stern hull type are known. The optimal value of the magnitude of the counter-rotating flow relative to the propeller changes depending on the sailing conditions, but in the case of a reaction fin fixed to the hull or an asymmetrical stern hull type, the angle of the fins and the stern hull may be adjusted at the time of new construction. Once the degree of twist of the propeller is determined, it is very difficult to readjust them later, and therefore it is impossible to arbitrarily adjust the magnitude of the counter-rotating flow relative to the propeller.

This idea was made in view of the above-mentioned circumstances, and was designed to improve propulsion efficiency by generating a counter-rotational flow against the propeller, and to adjust the magnitude of this counter-rotating flow at will. The purpose is to provide a propulsion performance improvement device.

The propulsion performance improvement device for a ship based on this invention consists of a pair of cylindrical or truncated conical rotors arranged almost vertically above and below the propeller center line in front of the propeller. It is designed so that it can be rotated independently.

As shown in Figure 1, when a cylindrical body 1 is placed in a fluid flow and rotated around the central axis, a lifting force L is generated, similar to when a wing is placed in the flow. At the same time, the flow flowing into the cylindrical body 1
It is known that the direction of V ₁ and the flow V ₂ flowing out from it change. By changing the rotation direction and rotation speed of the rotating cylindrical body 1, the direction and magnitude of the flow _V2 flowing out from the cylindrical body 1 can be changed. The same applies when a truncated cone is used instead of a cylinder.

When a ship's propeller rotates clockwise when viewed from the rear, the flow after the propeller becomes a rotational flow, and above the propeller center line, it flows diagonally from the left side to the right side.
Below this point, it flows diagonally from the right gen to the left gen.
Therefore, by rotating the upper rotor clockwise when viewed from above and rotating the lower rotor counterclockwise when viewed from above at approximately the same speed, counter-rotation with respect to the propeller is achieved, as explained next. This generates a flow, which reduces the rotational flow in the wake of the propeller and improves propulsion efficiency. That is,
Above the propeller center line, the upper rotor, which rotates clockwise when viewed from above, creates a flow from the right side to the left side, and below this, the lower rotor, which rotates counterclockwise when viewed from above, causes a flow to the left side. A flow is generated from the bottom to the right side, and the direction of the rotational flow due to these is opposite to the direction of rotation of the propeller, that is, the direction of the rotational flow in the wake of the propeller. Therefore, the rotational flow downstream of the propeller is reduced, and the propulsion efficiency is improved. Furthermore, by changing the rotational speed of the rotor, the magnitude of the counter-rotational flow relative to the propeller changes.

As mentioned above, according to the device of this invention, by rotating the upper and lower rotors in opposite directions in a predetermined direction, a counter-rotational flow to the propeller is generated, similar to conventional reaction fins and asymmetric stern hull types. This can reduce the rotational flow behind the propeller and improve propulsion efficiency. By changing the rotational speed of the rotor, the magnitude of the counter-rotational flow following the propeller can be adjusted as desired. Furthermore, when a ship is used for a long time, the bottom of the ship and the surface of the propeller become dirty with deposits and frictional resistance increases, which increases the propeller torque and prevents the rotational speed of the propeller from increasing. For this reason, in the past, deposits on the bottom of the ship and propeller surfaces were removed at predetermined intervals, and new paint was applied to smooth the bottom and propeller surfaces.
In some cases, the propeller rotation speed is adjusted by cutting off the tips of the propeller blades or reducing the pitch of the blades. However, according to this invention, by changing the rotational speed of the rotor and changing the magnitude of the counter-rotational flow to the propeller, that is, the inflow angle, there is no need to cut off the tip of the propeller blade or reduce the pitch of the blade. , the propeller rotation speed can be adjusted.

An embodiment of this invention will be described below with reference to FIG.

FIG. 2 shows the stern part of the ship, in which a pair of cylindrical rotors 11,
12 are arranged almost vertically. Both upper and lower ends of the upper rotor 11 are rotatably supported by the arch 13 and boss 14 of the stern aggregate, respectively, and both upper and lower ends of the lower rotor 12 are rotatably supported by the boss 14 and the show piece 15 of the stern aggregate, respectively. Supported. Each of the rotors 11 and 12 is connected to a suitable drive device such as an electric motor or a hydraulic motor via, for example, a bevel gear, so that the rotors 11 and 12 can rotate independently about their respective central axes. Further, the rotational direction and rotational speed of each rotor 11, 12 can be changed arbitrarily.

In the above, during navigation, the upper rotor 11 rotates clockwise when viewed from above, and the lower rotor 12 rotates counterclockwise when viewed from above. In this way, as described above, a counter-rotational flow with respect to the propeller 10 is generated, which reduces the rotational flow downstream of the propeller and improves the propulsion efficiency. Note that the water flow in front of the propeller 10 is affected by the shape of the ship at the stern and is not necessarily uniform above and below the propeller center line, so the rotational speeds of the upper and lower rotors 11 and 12 at this time are not necessarily the same. . Furthermore, by changing the rotational speeds of the rotors 11 and 12, the magnitude of the counter-rotational flow to the propeller 10 can be arbitrarily adjusted depending on the navigation state.

The rotors 11, 12 may have a truncated cone shape, and the configuration for supporting and rotating them is as follows:
The present invention is not limited to the above embodiments, and may be modified as appropriate.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining the principle of this invention, and FIG. 2 is a side view of the stern portion showing an embodiment of this invention. 10...Propeller, 11,12...Rotor.

Claims (1)

[Scope of utility model registration request] It consists of a pair of cylindrical or truncated conical rotors 11 and 12 arranged substantially vertically above and below the propeller center line in front of the propeller 10, and these rotors 11 and 12 are separately arranged around their respective central axes. A device for improving the propulsion performance of ships that is capable of rotating.